Magnetic melanin nanoparticles as activatable theranostics for PET/MRI/PA tri-modal imaging guided photothermal therapy

FARE Award Winner

Authors

• P Huang
• H Hu
• J Lin
• G Niu
• X Chen

Abstract

Background: The separation of tumor diagnosis and treatment is one of major issues in the clinic. Herein, we report a radionuclide 64Cu labeled magnetic melanin nanopaticles (64Cu-MMNPs) for positron emission tomography (PET), magnetic resonance (MR), and photoacoustic (PA) tri-modal imaging guided photothermal therapy (PTT) of U87MG glioblastoma cancer. Methods: MMNPs were synthesized by biomimetic synthesis method using bioploymer melanin as the biotemplate. The radionuclide 64Cu was labeled with MMNPs by the high affinity of metal ions of melanin. PET, MR, and PA imaging were carried out on U87MG tumor-bearing mice. PTT was conducted both in vitro and in vivo. Results: MMNPs were successfully synthesized by biomimetic synthesis method. The size of MMNPs is ~15 nm. The r2 value of MMNPs is 163 mM-1 s-1, which is much higher than spherical magnetic nanoparticles (16 nm, r2=125.86 ± 9 mM-1 s-1; and 10 nm, r2=59.91 ± 6 mM-1 s-1). MMNPs were successfully radiolabeled with 64Cu and purified to give radiochemical yield ~100%. 64Cu-MMNPs were stable in PBS and mouse serum up to 24 h. In vivo PET imaging showed high tumor uptake of MMNPs after intravenous injection (150 µCi, 9.5%ID/g, 24 h). MRI and PA imaging also showed high tumor uptake of MMNPs. Afterwards, upon localized laser irradiation (808 nm, 0.5 W/cm2, 5 min), 100% tumor elimination was achieved in MMNP treatment group (10 mg/kg of MMNPs). Conclusion: MMNPs showed great potential as cancer photoactivatable theranostics with PET/MRI/PA multi-modality imaging capability and potent PTT effect.

Scientific Focus Area: Biomedical Engineering and Biophysics

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